Superconductor imaging surface magnetometry

The presence of superconducting surfaces in the vicinity of current sources may be interpreted in terms of image theory. This concept has both experimental and theoretical practicality. Experimentally, sensing coils for magnetic detection, when placed near such surfaces, perform in a gradiometric fashion. In order to explain this effect explicitly, a theoretical treatment of the magnetic fields in the presence of superconducting surfaces and coils is presented. Expressions are derived for planar and spherical geometries that approximate practical experimental situations. These expressions may be used to predict the expected gradiometric response of a coil as a function of the positions of the source and coil relative to the surface.